NO125397B - - Google Patents

Description

Nitrided material with good cutting edges

and wear-resistant properties.

The present invention relates to a new group of nitrided ternary or higher alloyed metals with good cutting and wear-resistant propertiesj and which consist of: (A) one or more metals from the group of niobium, tantalum and vanadium,

(B) titanium, and

(C) molybdenum or tungsten or both

in the subsequently specified quantities, which are in percentage by weight. One has

discovered that when such alloys are nitrided as described here, very useful cutting materials are formed (although they can also be used for other purposes), and these materials have significant advantages

with regard to duration, processability and costs in relation to previously known cutting tool materials, and in particular sintered carbides. In addition to this, the materials of the invention have excellent wear-resistant characteristics, which will be described below. Those skilled in the art will immediately appreciate the commercial and technical importance of the present invention. In addition to this, a new group of very advantageous alloys has been discovered.

As far as is known, no materials of the type described in the present invention have been mentioned in previous literature. Furthermore, no allusions to nitrated alloy compositions of the type described here have been found, or any applicability of such alloys. On the contrary, one finds certain descriptions which would indicate that nitrided alloys according to the present invention would be too brittle to be used, and it is consequently with some surprise that it has now been discovered that such materials can be very useful.

However, it should be noted that, in general, it is known that various metals and alloys can be reacted with elements such as carbon, oxygen and nitrogen in order to thereby improve surface properties or, in certain cases, to develop certain composite materials. Previously known work along these lines has in most cases involved a carbonization or nitriding of ferrous materials, and there is a relatively large literature concerning this field.

In previously known methods, the element carbon, nitrogen or oxygen has usually been in the gaseous phase. Reaction temperatures vary from as low as H25°C for ferrous metals to from 1925° to 2770°C for tantalum and tungsten. (See M.R. Andrews, J*Am. Chem. Soc. 5^: 18-45 (1932), as well as US Patent No. 3,163,563). The reaction product can be a continuous nitride, carbide or oxide layer on the metal surface, or an internal dispersion of the aforementioned elements and the metal, or a combination of these two types.

It is also known that if an alloy consisting of copper with smaller amounts of aluminum is exposed to oxygen at elevated temperatures, then the oxygen goes into solution on the alloy surface, diffuses into it and reacts with the aluminum to form an aluminum oxide dispersion in a copper matrix. A similar effect occurs when molybdenum, alloyed with smaller amounts of titanium and/or zirconium (ie up to 1.5%) is exposed to molecular nitrogen at elevated temperatures. In this case, a dispersion of titanium nitride and/or zirconium nitride is found inside the molybdenum. (See A.K. Mukherjie and J.W. Martin, J. of the Less Common Metals, 393 (19"60). With these minor additions, dispersion-strengthened materials are produced..

It is also known that if the elements tantalum, niobium or titanium are nitrided at elevated temperatures, or titanium alloys are diluted, this usually results in the formation of continuous, hard nitrided surface layers on the metals. These layers are usually relatively brittle. If tantalum is similarly carbonized,

then this results in the formation of a hard continuous carbide surface layer. If, however, the tantalum is alloyed before the carbonization,

then a significant improvement is achieved with regard to the adhesion of the resulting layer to the substrate. (See US Patent No. 3,163,563). Similar improvements and modifications with regard to phase distribution and adhesion of the surface layer have been observed when niobium is alloyed with zirconium or titanium before oxidation.

In contrast to this previously known technique, the present invention mainly concerns the production of an exceptionally useful group of materials, which arise from a reaction between certain alloys and nitrogen. Such alloys contain niobium (Nb) and/or tantalum (Ta) and/or vanadium (V) as a constituent. Titanium (Ti) is the other component. A smaller amount (up to 3%) of the titanium can be replaced with zirconium (Zr). The third principle component is molybdenum (Mo) or tungsten (W) or both. Smaller amounts of other materials and/or metals may also be present, either as impurities or as harmless dilutions, which do not affect the material's special properties. After the present material has been nitrided, it is characterized by a very desirable and advantageous combination of mechanical properties which make them very usable and especially under conditions which include very hard wear or abrasion. The invention further covers certain new alloy systems per se.

It should also be noted that prior art and literature indicate that when the metals niobium, tantalum, vanadium or titanium are reacted with molecular nitrogen at elevated temperatures at 1 atmosphere pressure, continuous nitride or subnitride layers are formed on the metal surface. In addition to this, individual particles of subnitride or solid solution phases can be found under said outer layer. Such nitrided metallic elements can in no way be compared with the nitrided materials according to the present invention with regard to properties and applicability. Although said outer hard layers have a certain hardness, their application is relatively limited. Their ability to bear mechanical stress is relatively poor as this can be measured by tests that include diamond penetration, metal cutting and abrasion or impact under high stress. The materials are further characterized by having poor strength, weak toughness and little resistance to peeling off shells and chips. As shown in the following, it has been found necessary to eliminate the continuity of the nitrided layers by using materials whose composition and properties are graded in an almost continuous manner in order to thereby obtain maximum results at the test conditions indicated in the following.

It has been found that really effectively nitrided materials according to the present invention can only be produced when certain combinations of metals in certain concentration ranges and conditions are present in the alloys prior to nitriding. As mentioned above, the alloys before nitriding must contain at least three metallic components, namely:

(A) one or more of the metals niobium, tantalum and vanadium,

(B) titanium, and

(C) one or both of the metals molybdenum and tungsten.

When niobium is used from group A alone, the content can vary from 10 to 85 percent by weight. (All percentages in the following are per weight unless otherwise stated). When tantalum is used alone, the content can vary from 10 to 88% and when vanadium is used alone, the content will vary from 15 to 90%,

For the alloys according to the present invention, where two or more of the group A metals are used, the combination ranges will also be indicated.

It has also been found that titanium must in all cases constitute

a relatively minor component of the three- or multi-component alloy system, ie the titanium must be present in amounts of less than 45% by weight, and in the preferred materials it is present in amounts considerably less than this. Furthermore, and this is a typical feature of the present invention, there must be less titanium present than either niobium or tantalum or both. When vanadium alone is used from group A, it has been possible to produce usable nitrided materials where there is somewhat more titanium than vanadium (V : Ti ratio

can be as low as 0.66; 1), but it is also preferred here that the vanadium content is higher than the titanium content. When two or more metals from group A are used together, it is further Toré drawn that their total content is higher than the titanium content.

A smaller amount, {ie, up to 3 50 of the titanium can be replaced with zirconium without the material's reversibility therefore decreasing;

If molybdenum is used alone from group C, then the amount can vary from 2 to 60% if the metal is used with niobium and/or vanadium, while the amount can vary -from 2 to 50%, if the metal is used with tantalum alone from the group A metals. If tungsten is present alone, the amount may vary from 2 to BO%. In a subsequent section, we will come back to the restrictions that are necessary when both molybdenum and tungsten are present in said alloy systems. The amount of molybdenum and 7 or tungsten that is necessary is further dependent on the amount of the other metals.

The present invention thus relates in particular to nitrided materials consisting essentially of the alloy system (Nb, Ta, V) -

(Ti[Zr]) - (Mo, W) and covers a number of advantageous and desirable composite materials varying from a three-component to a seven-component alloy system if the zirconium replaces part of the titanium. In addition to this, minor impurities or diluted metals may be present in the alloy which do not affect the desirable properties of the nitrided materials.

Within the aforementioned range of variation, there are certain preferred compositions which to a higher degree than others satisfy the relatively strict test criteria with regard to cutting that have been used, or there are materials which are particularly resistant to wear or abrasion, or there are materials which can be manufactured more easily than second. After nitriding, all available materials in the alloy system can be used for cutting tools, but there are also other aspects of the present invention which are very important.

According to the present invention, a nitrided material with excellent cutting and wear-resistant properties is provided, consisting of a metal from each of groups A, ~B and C where group A consists of niobium, tantalum and vanadium, group B is titanium "of which up to 3% can be replaced with zirconium, and group C consists of molybdenum and tungsten, which material contains at least one mg of nitrogen per cm of surface, and this nitrided material is characterized by:

(a) when only niobium and molybdenum are present together with titanium, the range of variation of the niobium content is from 20 to 85%, (b) when only niobium and tungsten are present together with titanium, the range of variation of the niobium content is from 10 to 85%, ( c) when only niobium, molybdenum and tungsten are present together with titanium, the minimum required content of niobium is determined by the formula:

10 (Ratio E) + 20 (Ratio D)

and the maximum content of niobium is 85%,

(d) when only tantalum and molybdenum are present together with titanium, the range of variation of the tantalum content is from 25 to 88%, (e) when only tantalum and tungsten are present together with titanium, the range of variation of the tantalum content is from 10 to 88%, (f ) when only tantalum, molybdenum and tungsten are present together with titanium, the minimum required content of tantalum is determined by the formula:

10 (Ratio E) + 25 (Ratio D)

and the maximum content of tantalum is 88 i!,

(g) when only vanadium and a metal from the group consisting of molybdenum, tungsten and combinations thereof are present together with titanium, the range of variation of the vanadium content is from 15 to 90%, (h) when more than one metal from the group niobium, tantalum and vanadium is present together with only molybdenum and titanium, the combined minimum content of the metals niobium, tantalum and vanadium is at least equal to 20 (Ratio A) + 25 (Ratio B) + 15 (Ratio C),

(i) when more than one of the metals from the group niobium, tantalum and vanadium is present only together with tungsten and titanium, the minimum combined content of the metals niobium, tantalum and vanadium is at least equal to

10 (Ratio A) + 10 (Ratio B) + 15 (Ratio C)

(j) when more than one metal from the group niobium, tantalum and vanadium is present together with molybdenum, tungsten and titanium, the minimum combined content of the metals niobium, tantalum and vanadium is at least equal to

[(Ratio A) + (Ratio B)] x

[ 10 (Ratio E) + 25 (Ratio D)] + 15 (Ratio C)

(k) when more than one metal from the group niobium, tantalum and vanadium is present, the maximum combined content of these is equal to or less than

85 (Ratio A) + 88 (Ratio B) + 30 (Ratio C)

(1) when titanium is present together with hare niobium and a metal from, the group "consisting of molybdenum, tungsten and combinations thereof, the titanium content varies. from. 1 to "45%, while the weight ratio of niobium to titanium is greater than 1, ( m) when titanium is present together with only tantalum and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the titanium content varies from 1 to 35 while the weight ratio of tantalum to titanium is greater than 1,

(n) when titanium is present only together with vanadium and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the titanium content varies from 1 to 45%, while the weight ratio of vanadium to titanium is greater than 0.66,

(o) when titanium is present together with more than one of the metals of the group niobium, tantalum and vanadium and a metal of the group consisting of molybdenum, tungsten and combinations thereof, the maximum content of titanium is equal to or less than

45 (Ratio A * Ratio C) + 35 (Ratio B)

and the weight ratio of the metals niobium, tantalum and vanadium to titanium must be equal to or greater than the ratio

(Ratio A) + (Ratio B) + 0.66 (Ratio C) : 1

and the minimum content of titanium is H,

(p) when only molybdenum, titanium and a metal from the group of niobium, vanadium and combinations thereof are present, the molybdenum content varies from 2 to 60%,

(q) when only molybdenum, titanium and tantalum are present, the molybdenum content ranges from .2 to 50% 3

(r) when only tungsten, titanium and a metal from the group consisting of niobium, tantalum, vanadium and combinations thereof are present, the tungsten content varies from 2 to 80%, and (s) when molybdenum, tungsten, titanium and a metal from group consisting of niobium, tantalum, vanadium and combinations thereof are present, the maximum combined content of molybdenum and tungsten is equal to or less than

60 (Ratio A + Ratio C)(Ratio D) +

50 (Ratio B)(Ratio D) + 80 (Ratio E),

and the minimum content of molybdenum and tungsten is 2%, and where

An important advantage of the present invention is that in one and the same material one achieves high hardness and wear resistance combined with good toughness or peeling resistance. It is normally very difficult to develop a good balance between these characteristics while keeping them at a relatively high level. The wide application of sintered carbides for cutting and wear-resistant purposes stems precisely from a balance between such properties. (However, it has been found that the present materials are far better and have a number of advantages over sintered carbides). Although ceramic materials such as alumina can be much harder than sintered carbide, their application is severely limited due to spalling and chipping.

Metal cutting tests have been used at 30.5 and 228.8 m/min. (at the surface) as a primary experimental assessment technique, as these conditions are very easily reproducible, apart from the fact that metal cutting will presumably be one of the principle areas of application for the present materials. Cutting hardened steel at high speeds - 228.8 m/min. - is a good measure of the material's wear resistance. At relatively low speeds (30.5 m/min), you get a very good assessment of the material's tendency to peel under load. These conditions will become more apparent from the following description.

It should be obvious that the present tests are relatively strict, but one has and has been able to develop a new type of materials that pass these test conditions with ease.

On the attached drawings are:

fig. 1 a ternary diagram for nitrided alloys in the niobium-tungsten-titanium system,

fig. 2 is a ternary diagram for nitrided alloys in the niobium-molybdenum-titanium system,

fig. 3 is a ternary diagram for nitrided alloys in the tantalum-tungsten-titanium system,

fig. 4 is a ternary diagram for nitrided alloys in the tantalum-molybdenum-titanium system,

fig. 5 is a ternary diagram for nitrided alloys in the vanadium-tungsten-titanium system,

fig. 6 is a ternary diagram for nitrided alloys in the vanadium-molybdenum-titanium system,

fig. 7 is a chart comparing the wear characteristics of one of the best sintered carbide materials with some of the present materials, and

fig. 8 is a diagram showing the microhardness of a variety of nitrided alloys in the Nb-Mo-Ti system.

Before proceeding with a detailed discussion of the present invention, it may be appropriate to first describe the experimental methods as well as the criteria used to determine the applicability of the present nitrided materials. Part of this description and part of the results could of course have been given as a series of examples (and should be considered as such), but for the sake of brevity the subsequent data will be presented in tabular form.

The alloys were melted in an argon atmosphere in an arc furnace using a water-cooled copper mold. Pure materials (purity higher than 99.5%) were used for all alloys, which usually weighed approx. 70 g. Some of the alloys were directly cold-rolled into a sheet of 0.3 cm. Other alloys were hot-rolled and planed before use. These methods are well known to those skilled in the art.

The processed alloys were cut into pieces of approx. 1 x 1 x 0.3 cm and reacted with molecular nitrogen at atmospheric pressure unless otherwise stated. The resulting structure, thickness and microhardness of the various reaction zones or layers were determined using standard metallurgical techniques. A variety of tests were used to assess the toughness and strength of the materials with regard to their use for purposes including abrasion and metal cutting.

The metal cutting tests were carried out on tool pieces of the same size as the aforementioned samples and with a 0.080 cm nose radius which was used as part of the cutting surface. Such radii were ground into the pieces before nitriding.

The alloys thus produced were then nitrided. For nitriding, a cold-walled furnace with a molybdenum heating element and radiation shields was used, and the furnace was evacuated to a pressure of 5 microns and purged with nitrogen before heating. The temperatures were measured with an optical pyrometer (Leeds and Northrup Optical Pyrometer, catalog no. 862), as the inspection took place on the unitized molybdenum heating element which completely surrounded the samples. All subsequent temperatures are therefore optically measured and uncorrected.

After nitriding, the test pieces were subjected to tests with surface velocities from 30.5 to 228.8 m/min. (at the surface) on an AISI 43^0 steel with a Rockwell C hardness of about 43 to 45. A feed rate of 0.012 cm per revolution and a depth of cut of 0.12 cm were used. A standard tool holder with a 5° backslope and a 15° side cutting angle was used. Tool wear was measured after a given amount of material had been removed.

For reasons that will be explained hereinafter, the principle criterion of whether present nitrided materials were satisfactory or failed, and thus whether they fell within or outside the scope of the present invention, was the ability to cut a given volume of the 4340 steel at both 30.5 - 228.8 m /min (at the surface). In Table I, this includes all materials not directly indicated as failed.

In the following description, the following conditions were used unless otherwise stated: (1) all nitriding was carried out in molecular nitrogen at atmospheric pressure, (2) the test pieces were of the size indicated above, (3) the first test involved removing 33 cm^ of the 4340 steel.

With a speed of 228.8 m/min. removed the best nitrided materials according to the present invention mentioned 33 cm^ steel during approx. 1 minute (it should be noted that the above and following speeds mean the linear speed at which the material passes the cutting edge).

For a comparison between typical cutting properties for a pair of materials according to the present invention and the hitherto best known sintered carbide (C6 quality), reference is made to fig. 7. This diagram shows that at 228.8 m/min. the carbide had a wear of more than 0.080 cm in 3 minutes, while one of the present nitrided niobium-tungsten-titanium alloys had far less wear even after 6 minutes of cutting.

When evaluating tools and tool material, failure is often considered to occur when the wear reaches around 0.08 cm. With materials according to the present invention, as indicated in tabular form and on the aforementioned graphic diagrams, a relatively strict test has been chosen, whereby the materials are designated as satisfactory (i.e. that they pass the test) when at a speed of 228.8 m/ my. (at the surface) has a uniform wear of less than 0.062 cm after removing 33 cm^ of steel. Although some shelling may occur in certain compositions when tested at 228.8 m/min, this tendency is greatly magnified at lower speeds and can be better estimated at 30.5 m/min. This is one of the reasons why two sample rates are chosen.

Development of an acceptable test criterion at this lower speed,” requires a somewhat more detailed comment. Materials that cut the desired 33 cm^ at the speed with little wear and no shell formation obviously pass the test. The materials that have large scale and chip formation and high wear along the cutting edge of the tool are considered to have failed. Furthermore, it has been shown that a number of materials satisfactorily cut the desired 33 cm^, but that at the lower speed severe shell and chip formations occur, and these materials consequently become progressively worse, and they are also considered to have failed. Other materials will show little peeling and chipping and slight wear along the cutting edge, but some limited microscopic peeling along the edge as soon as 8 cm^ of metal has been removed. However, the toughness of the material is sufficient so that this initial wear does not develop further. Up to 96 cm^ of metal has been removed by cutting, and little change has been found with regard to the wear of the cutting edge in certain types of materials. These types of materials are indicated as satisfactory or marginal depending on the amount of wear and tear that occurs.

Table I presents cutting test results for some of the present materials as well as some others after removing 33 cm^ of hardened steel at 228.8 and 30.5 m/min. (at the surface). All mentioned alloys were nitrided in molecular nitrogen at the indicated temperatures (as measured by the aforementioned optical pyrometer) for the indicated time period.

Although a reaction between various alloyed compositions and molecular nitrogen at atmospheric pressure has been described so far, it is of course also possible to use other nitrogen sources than the pure diatomic gas to produce the present nitrided composite materials; the nitrogen can e.g. be present as a relatively small component in a gas mixture. One has e.g. nitrided specimens of Nb - 20 W - 30Ti at 1Q80°C for 2 hours in both argon - 5% nitrogen and argon - 2\% nitrogen with a resulting nitrogen absorption of 18 and 20 mg/cm 2 respectively, compared to 18 mg/cm p for the same type of material when this was treated in 100% nitrogen. In all cases, a usable cutting tool was produced.

Heat treatment variables can also be used to change the nitration reaction kinetics and to modify the reaction product. It has been found that by using certain heating and cooling rates, several heat treatments in nitrogen and finishing treatments, certain improvements can be made in the present materials.

When e.g. Nb-20W-30Ti was nitrided at 2385°C for 2 hours and then annealed in argon for 1 hour, then some improvement was obtained in terms of peeling resistance when tested at 30.5 m/min. (at the surface).

Due to the relatively wide variations with respect to the alloy compositions, however within certain limits as these are indicated in the following, nitriding at different temperatures and time periods may be necessary to develop high-quality materials according to the present invention. Typically, microhardness, metallurgy, hardness and weight gain will be data that can be used to select usable nitriding treatments.

To produce usable nitrided composite materials

in present alloy systems, it has further been found that the nitrogen absorption must be at least 1 mg/cm 2 surface area, although higher amounts are preferred, the surface microhardness should be greater than 100 diamond pyramid number (DPN), and the reaction depth to which such hardness is developed should be at least 0.012 mm.

Another important feature for a full understanding of the present invention concerns the relative nitrability of the various metallic constituents in the alloy systems. With an application of the present invention, one must take these conditions into account. With regard to the nitride reaction, metals such as molybdenum and tungsten can be said to be relatively inert, niobium, tantalum or vanadium can easily be nitrided, while titanium is most reactive with nitrogen. During nitration, a certain distribution of the nitrogen is found, all depending on the reactivity of the substrate. Because of this, and this can also be demonstrated by the experimental results, the amount of titanium should be limited in relation to the other components. If the molybdenum and tungsten content is increased, then the nitriding reaction will usually decrease proportionally.

When one thus considers the present invention and the experimental results indicated here, it is necessary to understand that the used nitriding temperature and time are in relation to the material being treated. The present description provides significant data with regard to these variables, but it should be noted that one must take into account the general principles according to the present invention when nitriding materials that fall within the scope of the invention, but which are not shown as an example here.

Another important feature to take into account is that relatively large amounts of niobium, tantalum and/or vanadium, and somewhat smaller amounts of titanium, as well as tungsten and/or molybdenum, can be present in the present alloy systems, while maintaining the high quality of the material. This is commercially important because many such alloys can easily be cold worked to the desired shape and then nitrided.

It is also an important feature of the present invention that the original shape of the test piece is retained during the high-temperature nitriding. With the present treatment, a dimensional growth of less than 1% can usually be observed, and for many materials the growth is considerably less, besides the fact that in a number of materials some shrinkage has been observed. During the nitration, one can thus only take into account the nitration conditions in order to achieve the desired properties, without taking into account possible side reactions.

Many of the available materials can be nitrided so that a composite structure is formed throughout the material with good toughness. However, the reaction can usually be limited to the outer area without a greater hardening of the core in the substrate. The minimum reaction depth depends on the subsequent application area, but it has been possible to demonstrate that the amount of reaction that is necessary for harsh applications such as e.g. the aforementioned shear test is relatively small.

The thickness of the alloy body will also affect the nitriding kinetics and the amount of nitrogen that must be absorbed in order to develop sufficient hardness for the material to be used for abrasion-resistant purposes and metal cutting. As the alloy becomes thinner, effective hardening can be carried out at a lower nitriding temperature and for a shorter time. This relationship applies whether the material is a free-standing body or a coating on another substrate.

As an example of this effect, the alloy Nb-30Ti-20W must be nitrided at 1Q80°C for 2 hours to develop a surface hardness of 1175 DPN to a depth of 0.025 mm when the thickness of the piece is 0.32 cm. If the thickness is 0.015 cm, the same hardness can be obtained to a depth of "^0.025 mm by a nitriding at 1760°C for 1 1/4 hours. The nitrogen uptake of these 0.32 and 0.015 cm thick samples was 18 and 5.6 mg/cm respectively

show.

The amount of nitrogen absorption that is necessary to achieve high quality is very strongly dependent on the alloy composition as well as on the thickness of the test piece. All subsequent alloys and treatments resulted in e.g. in excellent cutting qualities when the pieces were 1 x 1 x 0.3 cm.

If alloys that require less nitrogen absorption are used as thin pieces, then of course the required nitrogen absorption will be correspondingly reduced, which can be shown for the alloy Nb-20W-30Ti.

The terms "preferred", "satisfactory" and "failed" have been used on the attached ternary phase diagrams.

By the term "preferred", as indicated on the diagrams by filled black circles, is meant specimens cutting at both 228.8 and 30.5 m/min. SFM with little wear.

The term "satisfactory", which is indicated by half black and half white circles on the diagrams, means test pieces that cut at both speeds, but that you get higher wear at one of the speeds. In most cases, this higher wear will be noticeable at 30.5 m/min. and is caused by microscopic shell and chip formation.

By the expression "failed", which is indicated on the diagrams by X, it is understood that the test piece fails due to high wear either at 228.8 m/min. or 30.5 m/min. or both places. These materials are not part of the present invention.

In what follows, some of the specific alloy systems that form part of the present invention will be described.

The niobium-tungsten-titanium system

A number of ternary alloys in the system Nb-W-Ti were reacted with nitrogen at elevated temperatures. The treatment conditions and the cutting test results are indicated in Table I, while the cutting test results are also shown graphically in fig. 1.

Compositions that fall within the polygon that is formed

of the lines ABCDE and A on fig. 1, covers all the niob.-tungsten-titanium-nitrided materials that passed the above test criteria, i.e. satisfactory cutting at both 228.8 and 30.5 m/min., as well as the preferred materials that passed these tests with very little wear.

From fig. 1, one can see that in such a nitrated ternary system, the following ranges of variation can be used:

From 10 to 85% niobium

from 1 to 45% titanium

and from 2 to 80% tungsten,

where the ratio of niobium to titanium is greater than 1:1.

Within this relatively wide range of applicable materials, the following compositions are found to be particularly useful as cutting tool materials, when subjected to suitable nitriding treatment:

From 24 to 75% niobium

from 3 to J>6% titanium

from 10 to 60% tungsten

where the ratio of niobium to titanium is greater than 1.5 "• 1.

Such a preferred region for Nb-10W alloys for cutting tools is illustrated by the inner polygon formed by lines H I J K L and H in FIG. 1, and it should be noted that within this inner polygon all nitrided materials are preferred with regard to the 30.5 and 228.8 m/min. criteria stated here, when they are nitrated on

an appropriate way.

The alloy Nb-31W-15Ti represents one of the preferred ternary compositions which can be nitrided to develop a type of usable composite material according to the present invention. When this alloy is nitrided at 19 80°C for 4 hours, a multiphase structure is developed, i.e. a structure consisting of two or more phases, and where these phases usually have different nitrogen contents as well as metallic contents, and which can be distinguished when they are observed in cross-section under a microscope using standard metallurgical techniques. As the unreacted alloys are usually in a single phase, the nitrided multiphase structure can be easily observed. Naturally, some hardening can also occur under the observed reaction zone. For said Nb-31W-15Ti alloy, the reaction zone was 0.75 mm deep.

To avoid misunderstandings, it should be noted that the term "phase", as used here, means a physically homogeneous and distinct part of a material system, and that the term "multiphase" means two or more such phases.

After such treatment, the Nb-31W-15Ti alloy had a high surface hardness that decreased to a reasonable depth.

Cutting tools made from Nb-31W-15Ti and treated as indicated above gave the following cutting results on a 4340 steel specimen at 228.8 m/min.:

These are naturally very good results under this test condition. One of the best sintered tungsten carbides (C6) was completely worn down and unsuitable for further cutting after removing the above amount of material at this rate.

A shear test was also carried out at 30.5 m/min. After removing 33 cm^ of material, the tool had only 0.012 cm of wear, and there was no evidence of peeling or chipping.

If the alloy composition is modified by replacing some of the tungsten with niobium, while keeping the titanium content at 15%, it was found that satisfactory materials were similarly produced by subsequent nitriding. Thus, an alloy with a composition of Nb-56W-15Ti, when nitrided for four hours at 1980°C, showed excellent cutting properties at both 228.8 and 30.5 m/min. The titanium content in the nitrided alloy can be increased to a certain extent while still producing satisfactory materials. As shown in table I, e.g. alloys with the compositions Nb-40W-20Ti and Nb-20W-30Ti are nitrided in order to produce usable tool material.

It has been found that when the alloy Nb-20W-30Ti is nitrided, high quality in terms of cutting properties can be achieved when sufficient weight gain and depth of reaction are achieved. Kinetic data for a 1 x 1 x 0.3 cm sample of this alloy was nitrided at a number of different temperatures as follows:

* As defined in "Metals Handbook" 8th ed. Vol. 1, (1961), page 660.

When the reaction takes place at 1870°C, the manufactured tool will not cut the steel satisfactorily either at high or low speeds. However, when the alloy is reacted at 1980°C for 2 hours, the alloy will easily cut steel at 228.8 ra/min. with a uniform wear of 0.010 cm after removing 33 cm and cutting at 30.5 m/min. was also better than before. When the alloy is reacted for 2 hours at temperatures significantly above 1980°C, there was little wear at 228.8 m/min, but there was a marked tendency to peel and chip formation, especially along the cutting edge. This brittleness became very noticeable at low speeds. When the composition was nitrided at 1980°C or 2045°C, there was strong shell and chip formation and the tool failed quickly at low speeds.

The behavior of this alloy is thus very sensitive to the amount of nitriding, but the composition can be easily processed so that it cuts satisfactorily.

For higher tungsten-containing materials, it has been found that

is a much greater range of variation with regard to the nitriding conditions, temperature and time, without deviating from the high qualities. This feature is very important, not only with regard to process control itself, but because the present materials can be used for a number of different types of metal cutting operations and for other purposes that require high wear and abrasion resistance. For the composition Nb-20W-30Ti, it has been found that if the tungsten content is lowered, ie below a certain level, or the titanium level is increased, then the resulting nitrided material will become progressively worse.

When e.g. the composition Nb-50Ti-20W is nitrided either at 1870° or 1980°C, then they will not cut the test steel either at high or low speeds. This result is expected, as there is more titanium than niobium in this alloy.

When the composition Nb-29Ti-1W is nitrided at 1980°C for 1 hour, it cuts satisfactorily at 228.8 m/min., but fails due to shell formation when tested at 30.5 m/min. At least 2% tungsten must be present.

While some minimal nitration is required to

achieve a usable combination of properties in the alloy Nb-40W-20Ti, then one finds that this alloy can be nitrided very hard without the produced material losing its ability to cut efficiently both at low and high speeds. Tools produced by nitriding at both 1980 and 2140°C showed excellent cutting properties and low wear at 228.8 m/min, and there was no localized failure or embrittlement. 30.5 m/min. The following data were obtained for such a Nb-40W-20Ti material:

Despite the fact that this material has been exposed to a significant difference in terms of degree of reaction, the material in both conditions shows excellent cutting ability. The significant difference in the properties of these cutting tools is further evident by comparing the hardness of the two materials.

Microhardness (DPN, 200 gram load)

The alloy that was nitrided for 2 hours at 1980°C thus had a moderate hardness, of a similar type to that found in sintered tungsten carbide, and the hardness decreased to a depth of less than

0.050 mm from the surface. If the material was nitrided at a higher temperature, a higher hardness was obtained to a greater depth. It is important that this wide variation in hardness can be tolerated in this composition while maintaining a high cutting ability.

For niobium-rich materials, a minimal amount of both tungsten and titanium is required to obtain a satisfactory nitrided material. The alloy Nb-10W-10Ti can be nitrided to produce composite materials capable of cutting efficiently at 228.8 m/min., but this material does not show very high quality at 30.5 m/min., and because of this and at due to the relatively high content of niobium, the material is not considered to be one of the preferred materials.

When the alloy nB-30W-8Ti is nitrided at 1980°C for 2 hours, it has high cutting ability at both high and low speeds. If the titanium content is reduced to lower levels, i.e. an alloy of the type Nb-38W-2Ti, then the cutting capacity decreases at both 228.8 and 30.5 m/min.

Alloys that fall within the above-mentioned preferred composition ranges can be nitrided to thereby produce materials with high wear resistance, and in cutting tools materials that are highly resistant to crater formation. Such crater formation can lead to rapid failure when the tool is tested under very harsh conditions,

i.e. at high speeds and loads. The crater resistance in the present materials can be achieved by a careful alloy composition and by greater nitriding in order to thereby produce a surface layer with greater strength.

In a nitriding of materials in this Nb-W-Ti system, it has been found that a nitriding at 1980°C for 2 hours for the preferred materials and those with a higher tungsten content gives excellent cutting tools. For niobric alloys, or those with a relatively low tungsten content, a lower nitriding temperature and/or shorter time is usually required.

Niob- mo ly bden- tl tan- sy the stone

The Nb-Mo-Ti system can, after a nitriding as described here, be fully compared to the Nb-W-Ti system with the fundamental difference that in the former system the niobium variation range is significantly smaller (20 - 85% compared to from 18 - 85%),

and that the maximum usable amount of molybdenum is somewhat less than that of tungsten (60% Mo in relation to 80% W). Apart from these compositional differences, the two alloy systems are, for the present purposes, essentially the same, which applies to all systems described herein, and the resulting properties are fully satisfactory in terms of the test criteria used herein. Within certain composition limits, the tungsten and molybdenum content are interchangeable, or both mentioned metals can be included in the same base alloy. Various examples of this alloy system with nitriding temperatures and times are given in Table I, while the cutting test results are graphically shown in Fig. 2.

Compositions that fall within the boundaries of the polygon formed by the lines ABCDEF and A in fig. 2 covers all niobium-molybdenum-titanium-nitrided materials that pass the above test criteria, i.e. satisfactory cutting at both 228.8 and 30.5 m/min., except that the preferred materials pass these tests with very little wear.

From fig. 2 it can be seen that in such a nitrated ternary system, the following composition ranges can be used:

from 20 to 85% niobium

from 1 to 45% titanium and

from 2 to 60% molybdenum,

where the ratio of niobium to titanium is greater than 1:1,

Within this relatively wide range of variation, it is found that the following compositions are preferred as cutting materials at 30.5 and 228.8 m/min., when they are nitrided as described here:

from 25 to 75% niobium

from 4 to 35% titanium and

from 8 to 60% molybdenum

where the ratio of niobium to titanium is greater than 1.6 : 1.

Such a preferred area for Nb-Ti-Mo alloys for cutting tools is illustrated by the polygon bounded in fig..2 by the lines H I J K L and H, and it should be noted that within this polygon all nitrided materials are preferred with regard to the criteria stated above, i.e. excellent cutting at both 30.5 and 228.8 m/min., when nitrided as described herein.

Within this composition range, it should be noted that an investigation started with the alloy Nb-20Mo-30Ti which was nitrided at 1980°C for 2 hours, whereby a multiphase nitrided composite was formed, and it could be determined that when the material was used as a tool for cutting in test steel, it passed both the aforementioned 30.5 and 228.8 m/min. criteria. Two alloys with almost the same niobium to titanium ratio as Nb-20Mo-30Ti were then produced and nitrided, namely:

58Nb-7Mo-35Ti, 1980°C for 2 hours

60Nb-OMo-40Ti, 1980°C for 2 hours.

It was found that when the molybdenum content decreased to 7%, the material retained its high cutting capacity at 228.8 m/min., although less chipping could be observed. Such chipping and shelling became more evident at 30.5 m/min., which indicates that the material's toughness had been reduced, although the material was satisfactory when compared to the alloy Nb-20Mo-30Ti, which was nitrided in the same time interval and at the same temperature. In this other alloy containing no molybdenum, it was found that the alloy would not cut effectively at any speed. Additional examples of nitrided binary niobium-titanium alloys that failed with respect to cutting are listed in Table I. Such alloys range from pure niobium to niobium-80% titanium which was nitrided for 2 hours at temperatures ranging from 1760° to 2090 °C. It should be obvious from this data that the presence of molybdenum and/or tungsten is critical if one wishes to produce nitrided alloys that contain niobium and titanium as other principal constituents.

The results further show that the necessary use of molybdenum and/or tungsten in the Nb-Ti system affects the microhardness variation in the composite materials. As mentioned earlier, one of the important features of the present materials is that they combine high effective surface hardness with a satisfactory gradation of this hardness into the body.

In this connection, reference should be made to fig. 8 which shows

a diagram of the microhardness variation in a pair of nitrided materials in the system Nb-Mo-Ti that were nitrided at 1980°C for 2 hours. From this diagram it can be seen that the most usable material of the three illustrated, namely Nb-20Mo-30Ti, has a high surface hardness (higher than 1500 DPN), which decreases continuously into the substrate. The alloy Nb-7Mo-35Ti similarly illustrates high surface hardness, and the alloy has a similarly comparable curve indicating that the hardness decreases inwards. When using the binary alloy 60Nb-40Ti, it appears that there is very low hardness under the outer layer of 0.025 mm. Although this outer layer has very high hardness and there is an abrupt discontinuity, the hardness of the outer layer could not be measured due to the brittleness of the layer.

In the Nb-Mo-Ti alloy system, it can be noted that particularly good cutting test results were obtained with the following nitrided materials:

60Nb-10Mo-30Ti, 1980°C for 2 hours

60Nb-20Mo-20Ti, 1980°C for 2 hours

60Nb-30Mo-10Ti, 1980°C for 2 hours

70Nb-20Mo-10Ti, 1980°C for 2 hours

70Nb-10Mo-20Ti, 1980°C for 2 hours

50Nb-20Mo-30Ti, 1980°C for 2 hours

40Nb-50Mo-10Ti, 1980°C for 2 hours.

Thus, when nitriding alloys in this Nb-Mo-Ti system, it has been found that nitriding at 1980°C for 2 hours for the preferred materials gives excellent cutting tools. For Niobricher alloys, or those with a relatively low molybdenum content, a lower nitriding temperature and/or a shorter period of time can usually be used.

Tantalum- woTfram- titanium- systernet

Various examples of this alloy system with nitriding temperatures and time intervals are given in Table I, while the cutting test results obtained are graphically shown in fig. J>>

As in previously mentioned alloy systems, compositions that fall within the boundaries of the polygon formed by the lines ABCDEF and A in fig. 3, cover all tantalum-tungsten-titanium-nitrided materials that pass the above criteria, i.e. satisfactory cutting at both 30.5 and 228.8 m/min., as well as the preferred materials that pass these tests with very low wear.

From fig. 3, it appears that in such a nitrated ternary system, the following composition ranges can be used:

from 10 to 88% tantalum

from 1 to 35% titanium

from 2 to 80% tungsten,

where the ratio of tantalum to titanium is greater than 1:1,

Within this relatively wide range of variation, it is found that compositions that fall within the below preferred range of variation are particularly usable as cutting materials, when they are subjected to suitable nitriding treatment as described here:

from 26 to 78% tantalum

from 1 to 34% titanium

from 5 to 60% tungsten,

and where the ratio of tantalum to titanium is greater than 1.8:1.

Such a preferred region for Ta-Ti-W alloys for cutting tools is illustrated by the inner polygon formed by the lines H I J K L and H in FIG. 3j and it should be noted that within this polygon all nitrided materials are preferred with regard to the 30.5 and 228.8 m/min. criteria mentioned here, when they are nitrated as described here.

Although this nitrided alloy system is clearly indicated and described in Table I and Fig. 3>, however, it may be appropriate to attach a couple of general remarks to the system.

It appears that the types of materials which cut the test steel very effectively at both 30.5 and 228.8 m/min. can easily be produced 1 nitrided materials which contain large amounts of tantalum and/or tungsten. At the same time, it has been found that an addition of as little as 2% tungsten to Ta-20Ti produces a marked increase in wear resistance and spalling resistance both at high and low speeds, when this alloy is compared with the pure binary alloy Ta-Ti.

To point out the importance of the tungsten addition (or the molybdenum addition to the ternary system described below), reference should again be made to Table I. Binary compositions consisting of tantalum and from 5 to 80% titanium were nitrided for periods of from 1 to 2 hours at temperatures varying from 1760°C to 2090°C. None of these compositions met the present test criteria.

As a comparison, it can be added that a 2% addition of tungsten made the alloys pass the mentioned criteria very easily, and with a content of 10% tungsten the ternary alloys were very good.

It should again be pointed out that another critical feature of the present invention is that the ratio of tantalum to titanium, just as in ternary niobium alloys, must exceed 1 if an effective and usable material is to be produced. From Table I it can be seen that the alloy Ta-20W-50Ti which was nitrided at 1980°C for 2 hours failed at both 30.5 and 228.8 m/min.

It should also be pointed out that the following alloys, which were nitrided at 1980°C for 2 hours, had excellent cutting properties under the present test conditions:

Ta - 25 W - 10 Ti

Take - 10 W - 20 Ti

Take - 18 W - 18 Ti

Ta - 29 W - 17 Tue

When nitriding materials in this Ta-W-Ti alloy system, it has thus been found that a nitriding at 1980°C for 2 hours in connection with the preferred materials, as well as those with a higher tungsten content, produces excellent cutting tools. For alloys richer in tantalum and those with a relatively low content of tungsten, lower nitriding temperatures and/or shorter nitriding times can be used.

Tant al- moTybden- 1itah- sys t emet

After nitriding, this alloy system can be fully compared to the previously described tantalum-tungsten-titanium system, and as in connection with the niobium-containing ternary systems, all or some of the tungsten content can be replaced with molybdenum with approximately the same result. The only difference in composition is that while tungsten in the system could vary up to 80%, the upper molybdenum limit in the present system is only 50%.

Various examples of this Ta-Mo-Ti alloy system with nitriding temperatures and time intervals are given in Table I, while the cutting test results are graphically shown in Fig. 4.

As previously described, all compositions that fall within the polygon formed by the lines ABCDEF and A in fig. 4, cover all tantalum-molybdenum-titanium-nitrided materials that pass the above test criteria, i.e. satisfactory cutting at both 228.8 and 30.5 m/min., and the preferred materials will also pass these tests with very low wear.

It appears from fig. 4 that in such a nitrated ternary system, the following composition ranges can be used:

from 25 to 88% tantalum

from 1 to 35% titanium

from 2 to 50% molybdenum,

and where the ratio of tantalum to titanium is greater than 1:1.

Within this wide range of usable materials, it has been found that compositions falling within the preferred range set forth below are particularly useful as cutting materials when subjected to nitriding as described herein:

from 39 to 78% tantalum

from 1 to 34% titanium

from 5 to 40% molybdenum,

and where the ratio of tantalum to titanium is greater than 1.8:1.

Such a preferred region for Ta-Mo-Ti alloys is illustrated by the inner polygon formed by the lines H I J K L and H in fig. 4, and it should be noted that within this polygon, all nitrided materials are preferred with regard to the aforementioned - 30.5 and 228.8 m/min. test criteria, when the alloys are nitrided as described here.

Among these tantalum-molybdenum-titanium alloys, particularly good cutting test results have been achieved with the following compounds,

which was nitrated at 1980°C for 2 hours:

Ta - 19 Mo - 9 Tl

Ta - 30 Mo - 10 Tue

Ta - 10 Mo - 20 Tue

When nitriding materials in this Ta-Mo-Ti system, it has consequently been found that a nitriding at 1980°C for 2 hours in connection with the preferred materials produces excellent cutting tools. For alloys richer in tantalum or those with a relatively low molybdenum content, lower nitriding temperatures and/or shorter nitriding times can usually be used.

Although more highly alloyed systems fall within the scope of the present invention, and are described in greater detail in the following, it should be noted at this point that, apart from relatively minor compositional variations at the outer limits, the aforementioned clearly shows that there are significant replacement possibilities among the metals that are used in the aforementioned ternary alloy systems. Within a wide range of variation, the molybdenum can be replaced in whole or in part by tungsten, or the tungsten by molybdenum. Likewise, tantalum can be completely or partially replaced by niobium, or niobium by tantalum. The presence of titanium is important and it should be noted that up to 3% of the titanium content can be replaced by zirconium.

Van ad i um- moly b d e n - 1 i t an - s y s t e me t

Various examples of this V-Mo-Ti alloy system with nitriding temperatures and times are given in Table I, while the cutting test results are graphically shown in Fig. 6.

As in previously described alloy systems, compositions that fall within the boundaries of the polygon formed by the lines ABCDEF and A in fig. 6 cover all vanadium-molybdenum-titanium-nitrided materials that pass the above test criteria, i.e. satisfactory cutting at both 30.5 and 228.8 m/min., and the preferred materials pass these tests with very low wear.

It appears from fig. 6 that in such a nitrated ternary system, the following composition ranges can be used:

from 15 to 90% vanadium

from 1 to 45% titanium

from 2 to 60% molybdenum,

and where the ratio of vanadium to titanium is greater than 0.66 : 1.

Within this relatively wide range of variation, it has been found that compositions falling within the preferred range indicated below are particularly useful as cutting material when subjected to nitriding as described here:

From 24 to 78% vanadium.

From 1 to 35% titanium.

From 11 to 60% molybdenum,

and where the ratio to titanium is greater than 1.5:1.

Such a preferred range for V-Mo-Ti alloys for cutting tools is illustrated by the inner polygon formed by the lines H I J K F and H in FIG. 6, and it should be noted that within this polygon all nitrided materials will be preferred with respect to the aforementioned test criteria, if they are nitrided as described here.

Within the aforementioned ranges of variation, it has been found that the alloy V-25Mo-10Ti represents one of the best materials when nitriding for two hours at 1537°C. A material of this type cut the hardened test steel very efficiently at both 30.5 and 228.8 m/min, and the following wear data were obtained:

All wear was uniform, there was no sign of localized peeling or chipping either on the tool nose or along the leading edge. Nitriding for four hours at 1537°C gave substantially the same results.

In this alloy system, it has been found that the vanadium content can vary within a very wide range, and usable cutting tools can be produced from nitrided materials as long as the specified titanium to molybdenum ratio in the alloy is taken into account. It appears from fig. 6 that as the Ti-Mo ratio decreases, the nitrided material will show improved toughness, and further it has been found that they can be nitrided within a wide temperature range and still cut hardened test steel at both high and low speeds. When the molybdenum content in the present V-Mo-Ti alloys is relatively high in relation to the titanium content, the nitriding activity, i.e. the ability to form nitride, will be reduced, and satisfactory surface hardness for cutting at 228.8 m/min was not developed. This was, among other things, the case with the alloy V-72Mo-8Ti, which does not fall within the scope of the present invention.

Furthermore, satisfactory surface hardness and cutting capabilities cannot be achieved in such alloys when the titanium content is too high, such as e.g. in the alloy V-15Mo-55Ti, even if nitriding gives a stronger reaction as can be demonstrated by metallography, and a greater increase in weight than for the alloy V-72Mo-8Ti.

If the vanadium content of this ternary system is maintained

of 65% while the ratio of titanium to molybdenum is increased, excellent cutting properties will be obtained in the nitrided materials. If the ratio eventually becomes too high, the cutting ability will tend to decrease. While the alloy V-17Mo-17Ti after nitriding for two hours at 1650°C gave a material that cut very well both at 30.5 and 228.8 m/min, the nitrided alloy V-2Mo-33Ti, although it was a satisfactory cutting tool, a tendency to shell at 30.5 m/min. when it was nitrided to give good cutting ability at 228.8 m/min. A further lowering of the molybdenum content results in a total failure.

It has also been found that while vanadium-rich alloys such as V-10Mo-10Ti, can be nitrated e.g. at temperatures between 1^30° and 1760°C for two hours to produce a satisfactory cutting tool (a slight tendency to flaking and chipping at 30.5 m/min), then alloys with a lower vanadium content, such as e.g. the alloy V-30Mo-20Ti is nitrided for different periods of time at temperatures varying from 1537 to 1760°C, to excellent cutting tools.

■If one therefore uses the present invention in practice, one must absolutely stay within the variation limits indicated on fig. 6.

It appears from Table I that both unalloyed vanadium and the binary alloys of vanadium (10-50) titanium, after nitriding for two hours at 1705°C, failed at 30.5 m/mih. the shear test in each and every case.

It should be pointed out that the following ternary alloys passed the above test criteria when nitrided for two hours at 1540°C:

Fri - 25 Mo - 10 Tue

Fri - 17 Mon - 17 Tue

The following alloys passed when nitrided at 1650°C for two hours:

Fri - 25 Mo - 10 Tue

Fri - 17 Mo - 28 Tue

Fri - 20 Mo - 24 Tue

Fri - 30 Mo - 20 Tue

The following alloys also passed very well: V-30Mo-20Ti nitrided for 4 hours at 1540°C and for 2 hours at 1760°C, and V-45Mo-15Ti, nitrided for 4 hours at 1650°C.

When nitriding materials in the aforementioned V-Mo-Ti system, it has consequently been found that nitriding at temperatures varying from 1540 to 1760°C for 2 to 4 hours produces excellent cutting tools. The vanadium-tungsten-titanium systernet.

Various examples of this V-W-Ti alloy system with nitriding temperatures and nitriding times are given in Table I, while the cutting test results are graphically shown in Fig. 5.

As in previously described alloy systems, the composition that falls within the boundaries of the polygon limited by the lines ABCDEFG and A in fig. 5 cover all vanadium-tungsten-titanium-nitrided materials that will pass the above test criteria, i.e. satisfactory cutting at both 30.5 and 228.8 m/min, and the preferred materials will pass these tests with very low wear.

It appears from fig. 5 et in such a nitrated ternary system, the following composition ranges can be used:

From 15 to 90% vanadium,

from 1 to 45% titanium,

from 2 to 80% tungsten,

and where the ratio of vanadium to titanium is greater than 0.66:1.

Within this wide range of applicable materials, it has been found that compositions falling within the preferred range indicated below are particularly useful as cutting tools when subjected to nitriding as described herein:

From 24 to 80% vanadium,

from 1 to 40% titanium,

from 5 to 60% tungsten,

and where the ratio of vanadium to titanium is greater than 1.4:1.

One such preferred region for V-W-Ti alloys for cutting tools, illustrated by the inner polygon formed by lines H I J K L and H in FIG. 5> and it should be noted that within this polygon all the nitrated materials will be preferred with regard to the above 30.5 and 228.8 m/min. test criteria when the materials are nitrated as described here.

One of the preferred alloys in this ternary system is the alloy V-20W-15Ti. Kinetic data for cutting pieces of this alloy which originally weighed approx. 2 grams and which were treated in molecular nitrogen, are the following:

The nitrided materials resulting from the above nitriding conditions cut the test steel very effectively at both 30.5 and 228.8 m/min, and it was found that the wear resistance at 228.8 m/min increased with increasing weight gain.

Within the composition ranges shown in fig. 5 (and as shown in table I), it should be pointed out that the following nitrided materials have proven particularly useful as cutting materials:

V - 10W - 10 Ti (1540°C for 2 hours)

V - 20W - 15 Ti (1650°C in " " )

V - 42W - 4.5 Ti " )

V - 20W - 24 Ti " )

V - 10W - 36 Ti")

V - 35W - 20 Ti (1540°C " " " )

V - 40W - 24 Ti ( " " )

V - 50W - 10 Ti ( 1650°C" " " )

V - 60W - 15 Ti (1540°C " " " )

From the aforementioned data, certain general reflections can be made with regard to the present nitrated ternary systems. The vanadium-containing alloys can usually be reacted at somewhat lower temperatures than the corresponding niobium or tantalum alloys, and excellent cutting performance is more easily achieved in the vanadium-containing systems at relatively low nitriding temperatures even with materials that are highly alloyed with tungsten.

More particularly, it can be noted that in preferred ternary vanadium alloys, nitriding at temperatures varying from 1540° to 1650°C for 2 hours will give very good cutting materials. For alloys rich in vanadium, or those with a relatively low content of tungsten, low nitriding temperatures and/or shorter nitriding times can be used. For compositions with a higher content of tungsten, i.e. outside the preferred range, nitriding was carried out at 1760°C for 2 hours in order to produce a usable cutting tool.

Higher alloy systems

Representative examples of higher alloyed materials according to the present invention, nitriding conditions and cutting test results on the Rc 43-45 test steel are indicated in table II.

The legend is the same as in Table I.

When you want to use higher alloy systems according to the present invention, you must use certain composition ratios and formulas to determine whether or not the material will satisfy the aforementioned cutting test criteria. These factors have been briefly mentioned earlier, but will now be described in more detail to give a fuller understanding of them. In the present description and subsequent claims, the following ratio shall have the following meaning: (ie the concentration of niobium in relation to the total content of niobium, tantalum and vanadium). In a similar way

When in present alloy systems there is more than one metal from the group niobium, tantalum and vanadium, the maximum total content in weight percent of these metals must be equal to or less than

85 (Ratio A) + 88 (Ratio B) + 90 (Ratio C)

and the minimum content of these metals when tungsten and/or molybdenum is present must be equal to or greater than

[(Ratio A) + (Ratio B)]

[10(Ratio E) + 25(Ratio D)] + 15(Ratio C)

When more than one metal from the group of niobium, tantalum and vanadium is present, then the maximum amount of titanium that can be allowed in the alloy system is equal to or less than the amount determined by the formula

45(Ratio A + Ratio C) + 35(Ratio B)

and the ratio between the content of such metals and the titanium content must be greater than the ratio determined by the formula

Ratio A + Ratio B + 0.66 (Ratio C) : 1

When both tungsten and molybdenum are present, the maximum amount of these metals is determined by the formula:

60(Ratio + Ratio C)(Ratio D) +

50(Ratio B)(Ratio D) + 80(Ratio E)

It should further be noted that when niobium alone is used from the group A metals and both molybdenum and tungsten are present, then the minimum required amount of niobium is determined by the formula

10(Ratio E) + 20(Ratio D)

In the present alloy systems, the minimum amount of titanium is 1% and the minimum amount of tungsten and/or molybdenum is 2%.

In what follows, it will be explained how such ratios and formulas can be used to determine usable composite materials according to the present invention.

As mentioned above, one of the better alloys is 37Nb-30V-8Mo-25Ti. If the aforementioned formulas are applied to this alloy, the following results are obtained:

The maximum permitted contents of Nb, Ta and V are then given by the formula

85(0.55) + 88(0) + 90(0.45) = 87

The real amount of Nb, Ta and V in such a system is

37 + 0 + 30 = 67 percent by weight,

and since this amount is less than the permitted 87 percent by weight, the requirement is met.

The lower limit for the total amount of Nb, Ta and V is determined by the formula

[0.55 + 0][10(0) + 25(1)1 + 15(0.45) = 20.50

and since the real amount of 67 percent by weight is greater than this

value, then the minimum requirement is also met.

The titanium content in the above specifically indicated alloy is 25%. The maximum titanium content is thus determined by the above formula and will be

45(0.55 + 0.45) + 35(0) = 45.0 weight percent

and as 25% by weight is less than 45.0% by weight, this requirement is met.

Another requirement for the titanium content is determined by the ratio

Ratio A + Ratio B + 0.66 (Ratio C) : 1

With the present alloy, this ratio is:

0.55 + 0 + 0.66(0.45) : 1 = 0.85 : 1

The real titanium content in relation to Nb, Ta and V = 67 : 25 or clearly greater than 0.85 : 1, whereby this requirement is also fulfilled.

In the aforementioned material, the total molybdenum and tungsten content is 8 percent by weight, and thus greater than the lower limit of 2 percent by weight. The maximum amount is determined by the formula

60(Ratio A + Ratio C) Ratio D + 50(Ratio B)(Ratio D) + 80(Ratio E)

Thus:

60(0.55 + 0.45) 1 + 50(0)(1) + 80 (0) = 60 percent by weight

Since 60 is greater than 8, this requirement with regard to molybdenum and tungsten is also satisfied.

The nitrided alloy 37Nb-30V-8Mo-25Ti thus falls within the scope of the present invention and has proven to be fully usable as described above.

If one now considers an alloy consisting of 30Nb-30Ta-30V-2Ti-4Mo-4W, and applies the aforementioned formulas, one gets: A |§ 0.33

B=|§=0.33

C = $ = 0.33

The actual amount of Nb, Ta and V is 90% by weight, while the total allowable amount is 85(0.33) + 88(0.33) + 90(0.33) = 87

This alloy would thus fall outside the scope of the invention.

It should be noted that the above conditions only need to be applied near the outer limit of the different ranges of variation, and only in higher alloy systems. The conditions should thus be used where more than one of the metals niobium, tantalum and vanadium is present, and where the total content of these metals with respect to the maximum amount is between 85 and 90%. If the content of group A metals is more than 90%, then they automatically fall outside the scope of the present invention and cannot be used in it. If the content of the group A metals falls in the range from 25 to 85%, then it is not necessary to apply the above formulas, naturally provided that the other restrictions are met. The formulas are again used when the total content of group A metals varies between 10 and 25%, however again under the assumption that more than one metal is present. If the total content of group A metals is less than 10, then the materials will again fall outside the scope of the invention.

Similarly, the formulas will only apply to the maximum titanium content, if tantalum is present and together with niobium or vanadium or both, and the amount of titanium varies between 35 and 45%, If the titanium content is greater than 45% by weight, then the material does not fall within the present invention, and if it is less than 35% but greater than 1%, then it is not necessary to apply the formula for the maximum required amount of titanium.

When only one or both of the metals niobium and tantalum are present, while vanadium is not present, then the ratio between the niobium and/or tantalum content and the titanium content must be greater than 1. One only needs to take into account ratios of less than 1, when these alloys contain vanadium.

In connection with the metals molybdenum and tungsten, where they are both used, and only niobium and/or vanadium are present, the present formulas only need to be used when the total content of Mo and W is between 60 and 80%. If the content of molybdenum and/or tungsten is between 2 and 60%, then the material is satisfactory according to the above test criteria and clearly falls within the scope of the present invention.

When tantalum is present alone of the group A metals, the formula only needs to be applied in terms of the maximum content of Mo and W, when there is more than 50% molybdenum and tungsten.

The applicability of one of the aforementioned higher alloy composite materials, namely 37Nb-30V-8Mo-25Ti, appears from the following table.

These samples have shown that very low tool wear is obtained even when the samples extend well beyond cutting the aforementioned 33 cm^. This very good result is achieved when the molybdenum content is 8% in the Nb-V-Mo-Ti alloy. In addition to this, Table II shows a number of excellent results for a number of complex alloys with a correspondingly low molybdenum content. As a comparison, it can be mentioned that the lowest molybdenum content in preferred compositions in the Nb-Mo-Ti and V-Mo-Ti systems is 8 and 11% respectively. It therefore seems that a synergistic effect occurs in these complex alloys.

Compositions which contain different combinations of these elements, and which at the same time fall within the general range which has been shown to be preferred in the ternary systems, are also preferred in these complex systems. A number of these preferred complex systems are shown in Table II.

In the present description, one has so far considered nitrided composite materials which cut the test steel at both 30.5 and 228.8 m/min. However, there are a couple of additional features of the present materials which will be described in what follows.

Within the indicated composition ranges, one finds a group of nitrided materials which overlap the preferred compositions and which also cut the test steel (Rc 43-45) at much higher speeds, and thus have considerable applicability as high-speed cutting materials. Nitrided alloys within this group contain at least 74% of the metals niobium, tantalum and/or vanadium plus titanium plus molybdenum and/or tungsten.

When niobium is used alone in its group, the content varies from 74 to 85%, tantalum alone varies from 74 to 88%, while vanadium alone varies from 74 to 90%. When two or more of such metals are present, the maximum content of this group will vary between 85 and 90%, and is determined by the formula

85(Ratio A) + 88(Ratio B) + 90(Ratio C)

as described above.

The titanium content varies from 1 to 24%, while the tungsten content and/or molybdenum content varies from 2 to 25%.

Cutting tests were performed on the test steel at 381.3 m/min with a feed rate of 0.012 cm per revolution and a depth of cut of 0.050 cm. The data obtained are shown in Table III.

It should be noted that all the above materials are significant

.better than said C-6 quality sintered tungsten carbide.

Most of these compositions fall outside the aforementioned preferred ranges for use at 30.5 and 228.8 m/min, for-

because they have a certain tendency to peel and splinter at low cutting speeds.

After nitriding, these materials can be considered ceramic-like. In addition to their usefulness for high-speed cutting purposes, they can also be used due to their abrasion-resistant properties.

The above desirable properties are found in certain compositional ranges in the present nitrated ternary systems,

In the system niobium-tungsten-titanium (fig. 1) these fast-cutting materials are found within the polygon formed by the lines M B C N

and M in the figure. With regard to composition, such materials can before

nitration is characterized as follows:

from 74 to 85% niobium

from 2 to 25% tungsten and

from 1 to 24% titanium.

In the niobium-molybdenum-titanium system (Fig. 2), usable high-speed cutting materials can be found within the polygon formed by the lines M D E N and M. Before nitriding, these materials can be characterized as follows:

from 74 to 85% niobium.

from 2 to 25% molybdenum and

from 1 to 24% titanium.

It should be noted, however, that the molybdenum and tungsten content is completely interchangeable in said niobium-titanium materials, as far as their use as high-speed and abrasion-resistant materials is concerned. Both molybdenum and tungsten may be present in a total amount varying from 2 to 25%.

In the tantalum-tungsten-titanium system (fig. 3), the above-mentioned high-speed cutting materials are found within the polygon formed by the lines M D E N and M in the aforementioned figure. Before nitriding, the aforementioned materials can be characterized as follows with regard to composition:

from 74 to 88% tantalum

from 2 to 25% tungsten and

from 1 to 24% titanium.

In the system tantalum-molybdenum-titanium (fig. 4), such usable, fast-cutting materials are found within the polygon formed by the lines PI D E N and K in the aforementioned figure. With regard to composition, these materials before nitriding can be characterized as follows:

from 74 to 88% tantalum

from 2 to 25% molybdenum and

from 1 to 24% titanium.

It should also be noted here that the molybdenum and tungsten content is completely interchangeable in these tantalum-titanium base materials, as far as this feature of the present invention is concerned, and both metals can be present in a total amount varying from 2-25%.

In the vanadium-tungsten-titanium system (fig. 5), said fast-cutting materials are found within the polygon formed by the lines M E F N and M on said figure. With regard to composition, these materials before nitriding can be characterized as follows:

~ V W W f

from 74 to 90% vanadium

from 2 to 25% tungsten and

from 1 to 24% titanium.

In the system vanadium-molybdenum-titanium (fig. 6) these fast-cutting materials are found within the polygon formed by the lines M D E N and M in the aforementioned figure. With regard to composition, these materials before nitriding can be characterized as follows:

from 74 to 90% vanadium

from 2 to 25% molybdenum' and

from 1 to 24% titanium.

Based on the fairly similar properties with regard to cutting hardened steel (Rc 43-45) at 381.3 m/min, one can point out certain general compositional principles from the above.

Firstly, regardless of other metals present, the titanium content will vary from 1 to 24%.

Second, in all such compositions the tungsten and/or molybdenum content may vary from 2 to 25%

Third, the minimum content of niobium, tantalum and/or vanadium is 74%.

The question that may arise concerns the upper limit of two or more metals in the group niobium, tantalum and vanadium with respect to their varying but interchangeable upper limit. If the combined content of two or more such metals is up to or less than 85%, then they are usable in all cases. The problem arises, however, when the content of two or more such metals amounts to between 85 and 90% in the alloy to be nitrided. For this provision, the same previous upper limit formula is used, namely that the content cannot be greater than

85 (Ratio A) + 88 (Ratio B) + 90 (Ratio C)

The important feature of the present invention is that certain selected alloy compositions can be nitrided, whereby excellent materials can be produced which pass the aforementioned tests. It is understood that such alloys can be produced by a number of different types of techniques such as casting, metal processing, coating, powder methods, etc. It is a very important advantage that the material can be directly hot or cold formed before it is nitrided. Certain selected composition ranges that are easy to nitride offer certain manufacturing advantages.

As mentioned earlier, some of the investigated alloys were directly produced into sheet either by hot or cold rolling before nitriding. All these materials were characterized by a hardness of less than 400 diamond pyramid number (DPN), which corresponds to approx. 70 on the Rockwell A scale (Ra).

It has been found that materials that fall within the aforementioned usable composition range as defined in fig. 1 - 6, and which have a Ti/Mo or W ratio greater than 1, satisfy this requirement, and are therefore processable. The following Table IV gives the hardness data obtained for representative samples of such alloys in the as-cast condition.

Taking into account the above, the present invention also includes those alloys which are both easily processable and which can be nitrided into abrasion-resistant and cutting materials. •

For a more detailed description and discussion with regard to the materials' workability, reference should again be made to the ternary diagrams, i.e. fig. 1 to 6.

In the niobium-tungsten-titanium system (Fig. 1), such preferred machinable materials are found within the polygon formed by

the lines P Q F A B P. Compositions falling to the left of the P Q lines are those with a titanium to tungsten ratio of 1 or greater. In terms of composition, such ternary alloys before nitriding contain the following:

from 33 to 85% niobium

from 2 to 33% tungsten and

from 7.5 to 45% titanium.

In niobium-titanium based alloys, the molybdenum is interchangeable with tungsten in the alloy system shown in fig. 1. With niobium-molybdenum-titanium, such machinable materials are defined by the polygon P Q B C D and P, and with regard to composition one finds the following:

from 33 to 85% niobium

from 2 to 33% molybdenum and

from 7.5 to 45% titanium.

Easily processable compositions in the tantalum-tungsten-titanium system are shown in fig. 3. One finds the alloys inside the polygon formed by the lines P Q B C D and P on the aforementioned figure, and with regard to composition the following is found:

from 34 to 88% tantalum

from 2 to 33% tungsten and

from 6 to 35% titanium.

Molybdenum addition to tantalum-titanium based alloys is shown in fig. 4. Said alloys are found within the polygon formed by the lines P Q B C D and P on the said figure, and with regard to composition the following is found:

from 34 to 88% tantalum

from 2 to 33% molybdenum and

from 6 to 35% titanium.

It appears from the above that all or some of the molybdenum can be replaced with tungsten.

In the vanadium- and titanium-based materials, i.e. shown in fig. 5 and 6, the tungsten and the molybdenum can likewise be exchanged for each other, be it completely or partially.

In fig. 5, these easily processable alloys are defined by the polygon P Q C D E and P, and the composition is as follows:

from 25 to 90% vanadium

from 2 to 37% tungsten and

from 6 to 45% titanium.

In the alloy system V-Mo-Ti, fig. 6, the aforementioned materials are found within the polygon PQBCDogP, and the composition is as follows:

from 25 to 90% vanadium

from 2 to 37% molybdenum and

from 6 to 4-5% titanium.

In easily processable alloys according to the present invention, it is critical that the ratio of titanium to molybdenum and/or tungsten must be equal to or greater than 1. This is easily seen by the line P Q in all the aforementioned ternary system diagrams.

Within such easily processable alloy systems, however, there is another more desirable group of alloys, namely those which are not only easily processable, but are also preferred cutting materials as defined above. These materials are of real commercial importance.

In the system Nb-W-Ti (fig. 1), such materials are found within the polygon formed by the lines R S I J and R, and the material consists of:

from 43 to 75% niobium

from 10 to 29% tungsten and

from 12.5 to 36% titanium.

Such preferred materials in the Nb-Mo-Ti system are those falling within the polygon R S I J and R in fig. 2.

Purely in terms of composition, this includes the following:

from 45 to 75% niobium

from 8 to 27% molybdenum and

from 12.5 to 35% titanium.

It should be noted that in said preferred alloy systems the ratio of titanium to molybdenum and/or tungsten is 1 or greater.

In the system Ta-W-Ti, such preferred ternary alloys fall

ings within the polygon R S I J and R in fig. 3> namely:

from 48% to 78% tantalum

from 5% to 26% tungsten and

from 11% to 34% titanium.

In the Ta-Mo-Ti system, such preferred alloys fall within the polygon R S I J and R of FIG. 4, namely:

from 48 to 78% tantalum

from 5 to 26% molybdenum and

from 11 to 34% titanium.

In the system V-W-Ti, such preferred ternary alloys fall within the polygon R S I J and R in fig. 5, and they have the following composition:

from 41 to 80% vanadium

from 5 to 29% tungsten and

from 10 to 40% titanium.

In the system V-Mo-Ti, such preferred ternary alloys fall within the polygon J R I and J of FIG. 6, and they have the following composition:

from 43 to 78% vanadium

from 11 to 28% molybdenum and

from 11 to 35% titanium.

In addition to the fact that said alloys are easily processed in the form of solid bodies, it should be noted that said alloys can also be produced by standard powder technology.

The applicability of the present nitrided materials as high-speed tool materials for hardened steel has been described. In addition to this, the materials can also be used for cutting other materials that are difficult to cut. Thus, many of the present nitrided materials will cut 33 cm^ from a cobalt-based alloy ("Haynes 25") at 122 m/min (at the surface) with very little tool wear, while sintered carbide under these conditions will fail. Testing has shown that the materials also have excellent abrasion resistance. The nitrated materials are also resistant to a number of strong acids. They can thus be used in conditions that include both corrosion and abrasion.

More particularly, the present nitrided materials can be used, among other things, in rotary files and circular saws, in taps, drills, punching tools, rotary gaskets, nozzles and pipe liners.

Claims (26)

1. Nitrided material with excellent cutting and wear-resistant properties, consisting of a metal from each of the groups A, B and C where group A consists of niobium, tantalum and vanadium, group B is titanium of which up to 3% can be replaced with zirconium, and group C consists of molybdenum and tungsten, which material contains at least 1 mg of nitrogen per cm 2 surface, characterized in that (a) when only niobium and molybdenum are present together with titanium, the range of variation of the niobium content is from 20 to 85%, (b) when only niobium and tungsten are present together with titanium, the range of variation of the niobium content is from 10 to 85% » (c) when only niobium, molybdenum and tungsten are present together with titanium, the minimum required content of niobium is determined by the formula: and the maximum content of niobium is 85%, (d) when only tantalum and molybdenum are present together with titanium, the range of variation of the tantalum content is from 25 to 88%, (e) when only tantalum and tungsten are present together with titanium, the range of variation of the tantalum content is from 10 to 88%, (f) when only tantalum, molybdenum and tungsten are present together with titanium, the minimum required content of tantalum is determined by the formula: and the maximum content of tantalum is 88% s (g) when only vanadium and a metal from the group consisting of molybdenum, tungsten and combinations thereof are present together with titanium, is the range of variation for the vanadium content from 15 to 90%, (h) when more than one metal from the group niobium, tantalum and vanadium is present together with only molybdenum and titanium, the combined minimum content of the metals niobium, tantalum and vanadium is at least equal (in ) when more than one of the metals from the group niobium, tantalum and vanadium is present only together with tungsten and titanium, the minimum combined content of the metals niobium, tantalum and vanadium is at least equal to (j) when more than one metal from the group niobium, tantalum and vanadium is present together with molybdenum, tungsten and titanium, the minimum total content of the metals niobium, tantalum and vanadium is at least equal to (k) when more than one metal from the group niobium, tantalum and vanadium is present, the maximum total content of these equal to or less than (1) when titanium is present together with only niobium and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the titanium content varies from 1 to 45%, while the weight ratio of niobium to titanium is greater than 1, (m) when titanium is present together with only tantalum and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the titanium content varies from 1 to 35%, while the weight ratio of tantalum to titanium is greater than 1, (n ) when titanium is present only together with vanadium and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the titanium content varies from 1 to '45%, while the weight ratio of vanadium to titanium is greater than 0.66, (o) when titanium is present together with more than one of the metals in the group niobium, tantalum and vanadium and a metal from the group consisting of molybdenum, tungsten and combinations thereof, the maximum content of titanium is equal to or less than and the weight ratio of the metals niobium, tantalum and vanadium to titanium must be equal to or greater than the ratio and the minimum content of titanium is 1%, (p) when only molybdenum, titanium and a metal from the group of niobium, vanadium and combinations thereof are present, the molybdenum content varies from 2 to 60%, (q) when only molybdenum, titanium and tantalum are present, the molybdenum content ranges from 2 to 50%, (r) when only tungsten, titanium and a metal from the group consisting of niobium, tantalum, vanadium and combinations thereof is present, the tungsten content ranges from 2 to 80% t and (s), when molybdenum, tungsten, titanium and a metal from the group consisting of niobium, tantalum, vanadium and combinations thereof are present, the maximum combined content of molybdenum and tungsten is equal to or less than and the minimum content of molybdenum and tungsten is 2%, and where 2. Material according to claim 1, characterized in that it consists of: 10 to 85% niobium, 2 to 80% tungsten and 1 to 45% titanium. 3. Material according to claim 1, characterized in that it consists of: 20 to 85% niobium 2 to 60% molybdenum and 1 to 45% titanium. 4. Material according to claim 1, characterized in that it consists of: 10 to 88% tantalum 2 to 80% tungsten and 1 to 35% titanium. 5. Material according to claim 1, characterized in that it consists of: 25 to 88% tantalum 2 to 50% molybdenum and 1 to 35% titanium. 6. Material according to claim 1, characterized in that it consists of: 15 to 90% vanadium, 2 to 80% tungsten and 1 to 45% titanium. 7. Material according to claim 1, characterized in that it consists of: 15 to 90% vanadium, 2 to 60% molybdenum and 1 to 45% titanium. 8. Material according to claim 1, characterized in that it consists of: 24 to 75% niobium 10 to 60% tungsten 3 to 36% titanium, where the weight ratio between niobium and titanium is greater than 1.5:1. 9. Material according to claim 1, characterized in that it consists of: 25 to 75% niobium 8 to 60% molybdenum 4 to 35% titanium, where the weight ratio between niobium and titanium is greater than 1.6:1. 10. Material according to claim 1, characterized in that it consists of: 26 to 78% tantalum 5 to 60% tungsten 1 to 34% titanium, where the weight ratio between tantalum and titanium is greater than 1.8:1. 11. Material according to claim 1, characterized in that it consists of: 39 to 78% tantalum 5 to 40% molybdenum 1 to 34% titanium, where the weight ratio between tantalum and titanium is greater than 1.8:1. 12. Material according to claim 1, characterized in that it consists of: 2 4 to 80% vanadium 5 to 60% tungsten 1 to 40% titanium, where the weight ratio between vanadium and titanium is greater than 1.4:1. 13. Material according to claim 1, characterized in that it consists of: 24 to 78% vanadium 11 to 60% molybdenum 1 to 35% titanium, where the weight ratio between vanadium and titanium is greater than 1.5:1. 14. Material according to claim 1, characterized in that (a) when only niobium, titanium and a metal from the group consisting of molybdenum, tungsten and combinations thereof are present, the variation range for niobium is 74 to 85%, (b) when only tantalum, titanium and a metal from the group consisting of molybdenum, tungsten and combinations thereof are present, the range of variation for the tantalum content is 74 to 88%, (c) when kelp vanadium, titanium and a metal from the group consisting of molybdenum, tungsten and combinations of these are present, the range of variation for the vanadium content is 74 to 90%, (d) when more than one metal from the group consisting of niobium, tantalum and vanadium is present together with titanium and a metal from the group consisting of molybdenum, tungsten and combinations of these, the combined minimum content of said first group of metals is 74% s while the maximum content of these metals is equal to or less than 85(Ratio A) + 88(Ratio B) + 90(Ratio C), (e) the titanium content is 1 to 24%, (f) the content of metal from the group consisting of molybdenum, tungsten and combinations of these make up 2 to 25%. 15. Material according to claim 14, characterized in that it consists of: 74 to 85% niobium, 2 to 25% tungsten and/or molybdenum, and 1 to 24% titanium. 16. Material according to claim 14, characterized in that it consists of: 74 to 88% tantalum, 2 to 25% tungsten and/or molybdenum, and 1 to 24% titanium. 17. Material according to claim 14, characterized in that it consists of: 74 to 90% vanadium, 2 to 25% tungsten and/or molybdenum, and 1 to 24% titanium. 18. Material according to claim 1, characterized in that the ratio of titanium content to molybdenum content, if only molybdenum is present, to tungsten content, if only tungsten is present, and to the combined content of molybdenum and tungsten, if both of these metals are present, is greater than 1. 19. Material according to claim 18, characterized in that it consists of: 33 to 85% niobium 2 to 33% tungsten and/or molybdenum, and 7.5 to 45% titanium. 20. Material according to claim 18, characterized in that it consists of: 34 to 88% tantalum, 2 to 33% tungsten and/or molybdenum, and 6 to 35% titanium. 21. Material according to claim 18, characterized in that it consists of: 25 to 90% vanadium, 2 to 37% tungsten and/or molybdenum, and 5 to 45% titanium. 22. Material according to claim 18, characterized in that it consists of: 43 to 75% niobium 10 to 29% tungsten 12.5 to 36% titanium, where the weight ratio between niobium and titanium is greater than 1.5:1. 23. ' Material according to claim 18, characterized in that it consists of: 45 to 75% niobium 8 to 27% molybdenum 12.5 to 35% titanium, where the weight ratio between niobium and titanium is greater than 1.6:1. ■ 24. Material according to claim 18, characterized in that it consists of: 48 to 78% tantalum 5 to 26% tungsten, molybdenum or combinations of these 11 to 34% titanium, where the weight ratio between tantalum and titanium is greater than 1.8:1. 25. Material according to claim 18, characterized in that it consists of: 41 to 80% vanadium 5 to 29% tungsten 10 to 40% titanium, where the weight ratio between vanadium and titanium is greater than 1.4:1. 26. Material according to claim 18, characterized in that it consists of: 43 to 78% vanadium 11 to 28% molybdenum 11 to 35% titanium, where the weight ratio between vanadium and titanium is greater than 1.5:1.